Electrostatic condenser



Sept. 18, 1928.

R. H. HOYT ELECTROSTATIC CONDENSER Filed June 14, 1926 Patented Sept.18, 1928.

UNITED STATES PATENT OFFICE.

i REGINALDHUNTER I-IOYT, 0F ROSLIN DALE, MASSACHUSETTS, ASSIGNOR T0WIRELESS SPECIALTY APPARATUS COMPANY, OF 0] NEW YORK.

BOSTON, MASSACHUSETTS, A CORPORATION ELECTROSTATIC CONDENSER.

Application filed June 14, 1926. Serial No. 115,863.

This invention relates to electrostatic condensers.

Its object/is to improve the construction at low cost. I s The inventionconsists of the process and product hereafter described in connectionwith the drawings, of which Fig. 1 is an exploded perspective view ofthe condenser stack showing the stacked foils, m and micas and the foilbunches projecting from opposite sides of the stack; r

Fig. 2 is a perspective of a pair of telescopfing open-sided -U-shapedclamps;

Fig. 3 is a perspective view of the stack of m Fig. 1 with the clamps ofFig. 2 telescoped in lace; P Fig. 4 illustrates the process of initiallyputting the condenser stack under desired compression and in maintainingsuch compression permanently by fusing together the pair ofclamping-members of Fig. l in their telescoping relation of desiredstack compression- Fig. 5 is a perspective view of the com- 2 pletedpermanently clamped condenser removed from the processing apparatus ofFig. 1" and Figs. 6 and 7 are side elevations as in Fig. 4 of thecondenser of Fig. 1, but showing a modified form of telescoping clampfused in permanent stack-compressing condition.

The nature of the condenser, in the form at present preferred, is shownin exploded per spective in Fig. 1, wherein there are alternat- Ftogether constituting a stack S. Preferably sheets E are of micasandsheets F of v metal foil as lead or tin. Successive foils F are ofopposite polarity and are separated from one another by a mica sheet E,and they project from opposite sides of stack S. At the ends of thestack are insulating end plates D of somewhat thicker mica dielectricthan sheets E. I

p The two simple members of the clamping system C of stack S are shownin Fig. 2, each (C and C being a U-shaped sheet of soft brass. These arealmost duplicates but the main portion of C is longer than the main andE are shown as they actually exist after ing dielectric sheets E andarmature sheets portion of C so that the legs of C can tele-- scope ashereinafter described in detail) inbeing stacked together and the foilsof each of the oppositely poled foil-bunches A are soldered together attheir ends. As yet, how ever, the stack S is not under compression,

altho the clamping members of Fig. 2 have suitable terminals connectedwith the foilr bunches of the stack, and projecting out of the casingfor connection suitably in circuit as dcsired. Such condensers are ofvery low sales prices and it is especially desirable to keep down thecost; but it is important, even in such condensers, to clamp the stackefii'ectively so as to maintain the capacity as constant as may be. Thisinvention is valuable in its simplicity involving the necessary lowproduction costs of material and labor while providing an effectivepermanent clamp.

All that is necessary is to apply the telescoping U-clamps as in Fig. 3and then solder their joints on by the process of Fig. 4 resulting inthe product of Fig. 5.

No particular casing means is required, but the ends of the stack S areleft exposed from the two U-clamps C C and the unit consisting of stackand clamp is ready for use altho as suggested above it may be placed inany convenient or suitable casing with or without an insulatingembedment.

In Fig. 3 the insulating end plates D of stack S are engaged by theinside faces of the main portions E (Fig. 2) of the two U- clamps, whichare open at their sides to perenough so that they overlap so as topermit useful results of the soldering operation of Fig. 4; also saidlegs L of inner clamping the pair of clamping members are long theopposite edge.

member C are short'enough so that in the positions (Fig. 3) of theirinitial application to the stack, they do not extend to the main body ofthe outside clamping member C thus such legs are free to move furtherwhen the stack with applied clamp of Fig. 3 is put under compression inthe swivcled vise in Fig. 4.

In Figs. 4-5 is illustrated the fact that there may be a slightclearance N between the overlapping portions of the legs L of the pairof clamps; this indicating that there is no need of close working fitsat these portions of the clamps, which lie on the sides of stack S, saidsides not being under compression; the clamping bein efl'ective only atthe stackends, and by t e main bodies of the clamps C C and not by theirlegs.

Under the above conditions, and without any special care or painsinvolving expensive time, labor or materials, the little condenser withclamps applied as in Fig. 3, is placed under compression in the swivelvise of Fig. 4. All that is advisable, for convenient soldering is thata pair of overlapping adjacent legs of the pair of clamps be located inthe vise so that it will lie in a horizontal plane, as shown in Fig. 4.With the stack and its clamp in that portion in the Vise and while theare under end compression in the vise, the sol ering is effected asshown in Fig. 4, i. e., the end of one leg L of the outer telescopingU-member Q is soldered to the outer surface of the adjacent le L of theinner telescoping U-member O suc soldering extending (Fig. 5) from oneedge of both legs clear across to While no particular form of apparatusfor holding the product under compression during soldering is necessary,yet the process is best effected in some sort of swivel vise as thatshown, because the process leads itself to successive solderings of bothpairs of adj acent clamp-Yegs'without releasing the prodnot from thecompression during the. entire processing between Figs. 3 and 5. Thus,after the soldering shown in Fig. 4 has been completed (on one pair ofadjacent legs), the vise is turned one hundred and eighty degrees,carrying with it the now partially clamped condenser, so that the as yetunsoldered joint at the bottom in Fig. 4 is moved to the top therebypermitting convenient soldering at the second and last joint, i. e.,convenient in the sense of having the cooperation of gravity instead ofthe reverse. WVhile no particular design of apparatus is necessary,therefore, it is a useful feature of the process, in addition to otherfeatures,to maintain the temporary compression of the stackuntil bothjoints are soldered, i. e., not to release the processing compressionafter only one of the two joints is soldered. While it might be possibleto do the latter without injury, (because it is not necessary to applyany very high degree of that simple, ordinary soldering is efficacious,

and that no more expensive clamping means, clamping pressure orapparatus is needed to maintain permanent compression on the stack thanthe single, open-sided, telescoping U- clamps of soft brass, with thetwo joints soldered as shown completed in Fig. 5. It may seem surprisingthat such soldered joints are suflicient to maintain such compressionagainst the expansive tendency of the'compressed stack to break thesoldered joint; but the result of actual commercial production inaccordance with the invention as above are so good that the constructoris advised to do as above; these good results being due, apparently, tothe design of the clamping members adapting them to be retainedpermanently in compressing relation with the stack by nothing but thesoldering of the joints as above.

It is to be noted that in addition to the permissive clearance N betweenadjacent clamp legs, thereby avoidingaccurate fitting, the same is thefact as between the inside of the legs of the inner telescoping clamp Cand the edges-of micas E at'those sides of the stack from which thefoil-bunches do not project, as indicated by the clearance M, Figs. 45.1 That is, no special care is needed as to exact uniformity ofdimensions of either clampmember or of the widths of micas E. The sixfaces of the completed condenser are divided into three pairs, each pairhaving opposite 105 faces; thus, the two opposite end stack-faces areengaged by the main bodies or intermediate portions C, C of the twoclamps, the two opposite faces from which the foil-bunches A of oppositepolarity project are left entirely 110 free of the clamps owing to theopen-sided character, of the entire clamping system C, and the other twoopposite faces of the stack of micas E are paralleled by the four legs Lof the two clamps which exist solely for the 115 purpose of permittingthe two clamps to be held together by the soldering in their permanentcompressing relation with the stack, the face-relation of the mica edgesand the legs of each clamping member being immaterial (there may bespaces M between them) provided only that the legs can telescope on thestack so as to put it under compression and can be fused together whilein compressing relation with the stack so as to maintain 125 the desiredcompression permanently.

The above is the preferred form of the invention and possesses theadvantages that the clamping system is the same shape as the mica stackand does not tend to bend over the outer 130 edges of the micas; alsoafter the fusing is effected there is no reduction of the compression onthe stack. But Figs. 6-7 show a modification having some advantages ofthe preferred form. There the telescoping clamp is-in a single piece andonly the two ends L f L telescope with one another. Fig. 6 shows such aclamp applied to a sheet stacklike that of Fig. l, in readiness to beput under compression in process as in Fig. 4, when the endof outer legL is to be soldered to the surface of the inner leg L as shown effectedin Fig. 7. The sides C 0 of this single-piece clamp correspond with themain bodies or bases (1 C ofethe clamping members of Fig. 2, and it istheir inner faces which engage stack end-plates D (Fig. 7 to put thestack under compression. In processing the device of Fig. \6 in the viseof Fig. 4, however, there is-no telescoping of two members at the part 0of the one-piece clamp; yet the clampmg system must yield somehow to thecomression, and that is (Fig. 7) via outward owing of clam portion Cwhich in somecases may not e too seriously disadvantageous. Thismodification does not permit such a weak clamp structure as the clamps(soft brass) of Fig. 2, and the single piece clamp should be such as toretain the bow in (1 permanently so that when released from the vise,portion C will not straighten out more or less and thereby release thestack from the desired compression to any material degree. To that endthe one-piece clamp of Figs. 6-7 may be made of thicker material, or ofany of the various Well-known metals or metallic alloys having greaterstiffness than the soft brass of the clamps of Fig. 2, or both thickeror stiffer. Or, if the inside dimension of clamp-portion C wereexactly-the length of the stack when compressed as desired, and if legsG C were in position sufliciently far apart initially to permitinsertion of the uncompressed clamp, then soft brass might be used forthe one-piece clamp and there might be no bowing of portion C; but theseconsiderations illustrate the fact that the form of clamping system ofFig. 1, is greatly to be preferred.

The words fused and fusing are employed herein in their ordinarytechnical si ificanoe to include soldering, welding, razing, etc.

I particularly point out and distinctly claim the part, improvement, orcombination which I claim as may invention or discovery, as follows 1. Aclamped sheet-stack condenser comprising a foil-stack andvtwo U-shapedmetal clampin members extending around the end faces and two side facesof the stack, the foilsheets projecting beyond the stack and beond theclamping members from the remaining two opposite sidefaces of thestack;. the

intermediate portions of the U-shaped clamping members engaging the endfaces of the stack; the end legs'of the clamping members telescoping oneanother at those opposite side faces of the stack from which thefoil-sheets do not project; and the ends of the outside end legs of theclamping members being soldered to the surfaces of the inside end legs;the intermediate portions of the U-shaped clamping members being spacedapart in positions holding the stack under end-to-end compression, andsaid soldering holding said intermediate portions in their clampingrelations to the end faces of the stack.

2. A clamped sheet-stack condenser comprising a stackof dielectrics andarmatures an a metal clamping means extending around the end faces andtwo side faces of the stack, the armatures projecting beyond the stackand beyond the clamping members from the remaining two opposite sidefaces of the stack; said clamping means having at a side face of thestack from which the armatures do not project, two overlapping ends andadjacent thereto two clamping portions engaging the end faces of thestack; and said overlapping ends being fused together; the

clamp-portlons which engage the endfaces of the stack being spaced apartin positions holding the stack under end-to-end compres-- sion and saidfusing holding said clamp-portions in their clamping relation to the endfaces of the stack.

3. A clamped sheet-stack condenser comprising a stack of dielectrics andarmatures and two U-shaped metal clamping members extending around theend faces and two side faces of the stack, the armatures projectingbeyond the stack and beyond the clamping members from the remaining twoopposite side faces of the stack; the intermediate portions of theU-shaped clamping members engaging the end faces of the stack; the endegs of the clamping members telescoping one another at those oppositeside faces of the stack from which the foil-sheets do not project; andthe telescoping end legs of the clamping members being fused together;the

intermediate portions of the U-shaped clamping members being spacedapart in positions ho ding the stack under end-to-end compression, andsaid fusing holding said intermediate portions in their clampingrelations to the end faces of the stack.

4. A clamped sheet-stack condenser comprising a stack and ametal-clamping means extending around the end faces and two side facesthereof, the armatures projecting from the stack beyond the clampingmeans; and said clamping means having, at a side face of the stack fromwhich the armatures do 1 not project, two overlapping ends and adjacentthereto two clamping por tions engaging the end faces of the stack; saidoverlapping ends being fused together and hold mg said clamping portionsin-clamping relation with the stack.

5. Clamping means for a condenser stack which comprises two U-shapedmetal clamping members the ends of which telescope one another atopposite side faces of the stack, the portions of each member which areintermediate their telescoping ends being adapt-- ed for clampinengagement with the end .faces of the stair; the openings between thetelescoping portions of said members being adapted to leave thecorresponding side faces of the stack exposed; and the telescoping endsat opposite side faces of the stack being fused together and therebyholding the intermediate clamping portions in clamping relation with theend faces of the stack.

6. In combination with a condenser stack, a band-shaped metal clampextending around the o posite end faces and two of the four side aces ofthe stack leaving the other two side stack-faces exposed; said clamphaving at least two mutually overlapping ends located at one side faceof the stack, said overlapping ends being fused together holding the twoclamping faces of the clamp in clamping relation with the end faces ofthe stack to which said clamping faces are adjacent.

In testimony whereof I hereunto aflix my signature.

REGINALD HUNTER HOYT."

